Spring Tube And A Spring Pack For Spring Mattresses

ABSTRACT

A spring tube ( 1 ) encloses in known way a plurality of springs ( 2 ) arranged side by side, with facing parts of the wall ( 11 ) of the tube ( 10 ) joined, between one spring ( 2 ) and a subsequent spring, by welding lines ( 12 ), so that each spring ( 2 ) is contained in a portion ( 13 ) of tube ( 10 ), closed and separated from adjacent portions ( 13 ). The welding lines ( 12 ) have a predetermined minimum width (L) and are cut from one side of the tube inwards, so that each of the closed portions ( 13 ), containing a spring ( 2 ), can be compressed without any effect on the adjacent portions ( 13 ). this improves comfort while using a mattress manufactured with grouped spring packs (S) obtained from the spring tube ( 1 ). According to a second preferred embodiment, the spring tube ( 1 ) is cut along the welding lines at both sides.

BACKGROUND OF THE INVENTION

The invention relates to the technical field concerning the productionof spring mattresses. In particular, the present invention relates to aspring tube and a spring pack obtained from the spring tube. The springpacks obtained from the spring tube are used to manufacture springmattresses.

DESCRIPTION OF THE PRIOR ART

According to a widely used constructive technology, the springs use tomanufacture spring mattresses are enclosed in a plastic tube, which keepthem firmly side by side at a prefixed reciprocal distance. This isobtained by welding the facing parts of the tube walls comprised betweenadjacent springs to each other, for example by ultrasonic welding, sothat each spring is contained in a portion of tube, closed and separatedfrom the adjacent portions.

Afterwards, the tube with the springs is cut into pieces to form springpacks having a selected length, and the spring packs are joined, side byside, so as to obtain an assembly formed by longitudinal and transversalrows of springs.

The joint between one spring pack and another is obtained, e.g. by aplurality of glue-spots, applied centered with respect to the springheight, in the touching areas between one spring pack and another.

The assembly of spring packs has length and width corresponding to thedimensions of the mattress to be manufactured.

Then, the assembly of spring packs is wrapped into the usual coverings,which form the mattress facings and sides.

The disadvantage of the mattress obtained according to the abovementioned constructive technique derives from the fact that the assemblyof springs does not resist elastically in homogeneous way, because theelastic reaction depends on whether the weight is applied prevailinglyextending longitudinally or transversally.

In particular, it is observed that the spring deformation diminisheswhen the weight is loaded more on the rows of springs arranged along thespring packs extension rather than on transverse rows formed by springsof different adjacent spring packs.

The reason lies in the different load conditions which the springs ofthe rows along the spring pack extension, for example the ones disposedlongitudinal along the mattress, must bear with respect to the springsof rows perpendicular to the mattress.

It appears that, for example, if a single spring is compressed, theadjacent springs belonging to the same spring pack will be alsopartially compressed by the tube.

Due to the compression of the first spring, the tube distributes part ofthe load to the adjacent springs, while no load is transferred to thesprings adjacent in transversal direction, since they belong todifferent spring packs, joined to each other, as already said, only inthe central area.

Because of these differences of the load distribution, a differentsoftness of the mattress results with the same load, depending onwhether the load is distributed in a longitudinal or transversal way. Inpractice, considering that a mattress is aimed at receiving a humanbody, the above mentioned softness asymmetry depends on the way in whichthe body lies on the mattress, thus affecting the comfort condition.

SUMMARY OF THE INVENTION

The object of the present invention is to propose a spring tube and aspring pack for mattresses shaped in such a way, as to avoid the abovementioned disadvantage, thus obtaining a homogeneous reaction of thesprings independently from the load orientation and distribution.

Another object of the present invention is to propose a spring tube anda spring pack obtained by technologies and apparatuses analogous to theones used for known spring packs, so as to keep the production costs atthe same level.

The above mentioned objects are achieved by a spring tube for springmattresses, including a continuous tube and a plurality of springsenclosed into the tube and arranged side by side, at a selecteddistance, with facing parts of the tube walls between one spring and asubsequent one, joined by welding lines, so that each spring iscontained in a respective portion of said tube, closed and separatedfrom the adjacent portions, with said spring tube characterized in thatlongitudinal cuts are made along said welding lines starting from atleast one side of the spring tube and extending inwards, to form atleast one tubular segment for each portion of said portions.

According to the invention, also a spring pack for spring mattresses,obtained by cutting the above mentioned spring tube, is claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristic features of the invention will be pointed out in thefollowing description of a preferred embodiment of the proposed springpack, according to what is proposed by the claims and with the help ofthe enclosed drawings, in which:

FIGS. 1 a and 1 b show partial, lateral views of the proposed springtube and spring pack in a first and a second embodiments respectively;

FIG. 2 is a partial, top view of a spring assembly obtained by aplurality of packs of FIG. 1;

FIGS. 3 a and 3 b show section views taken along the section linesIII-III of FIG. 2, with an exemplification stress acting on a singlespring of the first and second embodiments respectively;

FIG. 4 is a section view taken along the section line IV-IV of FIG. 2,with the stress of a single spring being pointed out.

BEST MODES OF CARRYING OUT THE INVENTION

Referring to the above mentioned Figures, reference numeral 1 indicatesthe spring tube from which the spring pack for mattresses proposed bythe invention is obtained.

The spring tube 1, like the known ones, includes a tube 10 of floppyplastic material, within which the springs 2 are enclosed and keptarranged side by side, at a selected distance.

The parts of the tube wall between one spring 2 and the subsequent one,are joined by welding lines 12, crossing the whole tube side to side,obtained e.g. by ultrasound welding. The welding lines are parallel tothe axes A of the springs 2, so that each spring is contained within aclosed portion 13 of the tube 10, separated from adjacent portions 13(FIGS. 1 a and 1 b).

According to the invention, the welding lines 12 have a width Lsufficient to assure the sealing of the portions 13 even after havingdone longitudinal cuts 120 along a center line of each portion 13.

According to a first preferred embodiment of the invention, better shownin FIG. 1 a, the cuts 120 are made starting from one side only of thetube and extend inwards.

The continuity of the tube 10, between one portion 13 and another, ismaintained by the central part 12A of the welding line 12, and theremainder of the welding line, extending from the central part up to theside of the tube opposite to the one having the cut.

The cuts 120 define in each portion 13 a tubular segment 130 which isseparated from the tubular segment 130 of the adjacent portions 13. Eachtubular separated segment 130 permits independent axial compression ofthe relevant spring 2, which do not interfere with the axial extensionof the adjacent springs of the same spring pack.

According to a second preferred embodiment, the cuts 120 start from boththe sides of the tube 10 and extend inwards along the welded portions 13for a predetermined depth H (see FIG. 1 b).

The continuity of the tube 10, between one portion 13 and another, ismaintained in this case only by the central part 12A of the welding line12, which is not reached by the cuts 120; according to the shownnon-limiting example, the extension of the central part 12A is about onethird of the total.

In this case, the cuts 120 define at both sides of the tube, in eachportion 13, two tubular, opposite segments 130, each of which has axialextension as the cuts 120.

The tubular segments 130 of each portion 13 are separated from theadjacent ones and permit independent axial compression of the spring 2,which do not interfere with the axial extension of the adjacent springs.

For both the embodiments, this feature is maintained unchanged alsoafter the preparation of an assembly P (partially seen in FIG. 2),formed by spring packs S obtained from prefixed lengths of the springtube 1, joined side by side to one another, until the length and widthdimensions of the mattress to be produced are obtained.

Joining one pack S to another is obtained, e.g. by glue-spots C, appliedfrom centered positions, with respect to the spring 2 height, up to theside of the tube without the cuts, for the first embodiment, as can beseen in FIG. 3 a, and only in centered positions with respect to thespring 2 height for the second embodiment, as it can be seen in FIG. 3b. In both cases, the glue spots C are applied along the touching areasbetween one spring pack and another.

It appears that the first embodiment, the one with the cuts 120 alongonly one side of the tube 1, permits application of more glue spots Cfor each portion 13, for example there are three glue spots C visible inFIG. 3 a, thus keeping the assembly joined with more strength.

The assembly P comprises longitudinal rows FL and transversal rows FTformed by the springs 2; according to the shown example, the springpacks S are arranged to form the longitudinal rows FL, however theresulting softness is exactly the same both in the longitudinalextension and in the transversal extension.

As it is clearly seen in FIGS. 3 a, 3 b and 4, a single spring 2 of eachlongitudinal row FL, or of transversal row FT, can be compressedindependently without transferring parts of the load to the adjacentsprings, unlike the spring packs of the prior art, mentioned in theintroductory note.

Subsequently, according to the known technique, the assembly P of springpacks S containing the springs 2, is covered with usual coverings (notshown), which form the mattress facings and sides. The advantageousfunctional aspect of the so obtained mattress lies in the fact that itoffers a homogeneous softness, and consequently improved comfort,independently from orientation of the body lying thereon.

Obviously, the proposed spring pack S obtained from the spring tube 1allows, if desired, to use springs 2 of different elastic reaction toobtain orthopedic mattresses with differentiated softness areas withdifferent softness degrees, as there are no effects due to the springinterconnections caused by the tube 10, which are present instead in thespring packs of known type.

The proposed spring tube can be produced with the same technologies andapparatuses already used for known spring tubes, with obviousadvantages. The cuts along the welded strips can be easily made in thesame welding station or in a subsequent one.

Consequently, the proposed spring tube and spring pack offer importantfunctional advantages, which improve the mattresses characteristics,with practically no cost increase.

However, it is understood that what above has a value of a not limitingexample, therefore possible detail changes remain in the same protectivescope defined by the claims below.

1. A spring tube for spring mattresses, including a continuous tube(10), and a plurality of springs (2) enclosed into the tube and arrangedside by side, at a selected distance, with facing parts of the tubewalls (11) between one spring (2) and a subsequent one, joined bywelding lines (12), so that each spring (2) is contained in a respectiveportion (13) of said tube (10), closed and separated from the adjacentportions (13), with said spring tube (1) characterized in thatlongitudinal cuts (120) are made along said welding lines (12) startingfrom at least one side of the spring tube (10) and extending inwards, toform at least one tubular segment (130) for each portion (13) of saidportions (13).
 2. A spring tube according to claim 1, wherein saidwelding lines (12) are made parallel to the axes (A) of the springs (2).3. A spring tube according to claim 1, wherein each cut of said cuts(120) is made in a central part of the relevant welding line (12).
 4. Aspring tube according to claim 1, wherein said welding lines (12) have apredetermined minimum width (L) sufficient to keep the relevant portions(13) sealed after the cuts (120) are made.
 5. (canceled)
 6. A springtube according to claim 1, wherein two opposite cuts (120) are made foreach welding line (12) starting from opposite sides of the spring tube(1) and extending inwards.
 7. A spring tube according to claim 6,wherein said opposite cuts (120) have equal length.
 8. A spring tubeaccording to claim 1, wherein said springs (2) have different elasticbehavior, so as to define differentiated softness areas.
 9. A springpack for spring mattresses, obtained by cutting the spring tube ofclaim
 1. 10. A spring tube according to claim 2, wherein each cut ofsaid cuts (120) is made in a central part of the relevant welding line(12).
 11. A spring tube according to claim 6 wherein said opposite cuts(120) extend inwards for a predetermined depths (H).